Considerable effort has been heretofore directed to the development of recovery methods for polyurethane scrap materials, particularly polyurethane foams including flexible, rigid and semi flexible foams. One approach in recovery of flexible foam utilizes low molecular weight aliphatic diol to thermally decompose the foam for subsequent processing. (See, for example, U.S. Pat. Nos. 3,983,087; 3,738,946; 3,632,530; 3,300,417; and 2,937,151).
In recovery of flexible foam by thermal decomposition with low molecular weight diol, a separation over a period of time of the decomposition product obtained into two liquid layers has not been an altogether satisfactory consequence. U.S. Pat. No. 3,738,946 describes such consequence and shows mitigation of its effect by preparing rigid foams from balanced proportions of the resultant layers. U.S. Pat. No. 3,983,087 alternatively used particular amounts of certain alkyl substituted low molecular weight diols to provide a single phase decomposition product that is said to be suitable for preparation of certain polyurethane products. U.S. Pat. No. 3,632,530 provides for separating the layers obtained from certain flexible foams by rather extreme reaction conditions and cooling of the dissolution product before further purification.
Each of the approaches in the above-identified patents while evidencing merit, does have certain drawbacks. For example, the type of alkyl substituted glycol utilized in U.S. Pat. No. 3,983,087 may be even more expensive than the polyol originally used in making the flexible foam. Moreover, the process of U.S. Pat. No. 3,738,946 apparently is not seen to be applicable to recycling scrap flexible foam back into products suitable for preparation of new flexible foam. Still further, the process of U.S. Pat. No. 3,632,530 appears to require extended periods for completion.
The method of this invention provides not only a more rapid procedure for recovery of desirable liquid polyol product from the flexible foam, but, furthermore a polyol product that is suitable for use in the preparation of new flexible foam. Rather than proceeding with conditions that necessitate formation of separate liquid layers after heating the flexible foam in the presence the low molecular weight diol, the method herein allows formation and use of a single phase dissolution product. Moreover, economic use of readily available diol is achieved.
Accordingly, it is an object of this invention to provide an improved method for recovery of flexible polyurethane foams as well as to provide improved products therefrom.